1. Field of the Invention
My invention relates to a vertical polygonal heat exchange chamber having at least one tapered portion that is lined, in a novel way, with water tube panels. My invention also relates to a novel method of lining a tapered portion of a vertical polygonal heat exchange chamber with such panels.
2. Description of the Related Art
In polygonal chambers having at least one tapered portion that narrows toward an opening of the chamber, it is difficult to line the tapered portion with water tube panels in an industrially, economically, and operationally efficient manner. Such chambers may be used, for example, for recovering heat from flue gases or from suspensions of flue gases and solids, such as in cooled polygonal cyclones of fluidized bed boilers.
European Patent Publication No. 0 481 438, U.S. Pat. Nos. 4,576,120, and 5,775,265 disclose several conventional ways of lining a tapered lower portion of a four-sided heat exchange chamber with water tube panels.
European Patent Publication No. 0 481 438 discloses a centrifugal separator operating as a heat exchange chamber and having a funnel-shaped lower portion lined with water tube panels. The centrifugal separator has a rectangular horizontal cross section, and the funnel-shaped lower portion of the separator is formed by bending one or both of two opposite panel walls inwardly. The other panel walls, meanwhile, are uniform in width and extend vertically downward to the lower edge of the tapered portion, where they are connected with horizontal headers or manifolds.
U.S. Pat. No. 4,576,120 discloses a heat exchanger having a similar construction to the centrifugal separator disclosed in European Patent Publication No. 0 481 438, except that portions of the vertical wall panels extending beyond the side edges of the inwardly-bending wall panels connect to horizontal headers, which are arranged in steps.
U.S. Pat. No. 5,775,265 relates to a cooling surface cladding for a polygonal chamber of a steam generator. The chamber has a rectangular horizontal cross section and is lined with a plurality of tube walls. The bottom portion of the chamber is tapered, with first and second pairs of opposite tube walls sequentially being angled inwardly. The tube walls are tapered continuously and are connected to a plurality of inclined headers.
As those skilled in the art will appreciate, the foregoing approaches are not readily adaptable for lining heat exchange chambers having more than four sides, such as hexagonal or octagonal chambers. Moreover, the inclination of the headers in the ""265 patent can cause problems if the headers contain a mixture of steam and liquid water, in which case the steam and liquid water may be unevenly diverted to separate portions of the headers.
My invention provides a novel, efficient way of lining a tapered portion of a vertical polygonal heat exchange chamber having more than four sides with simple water tube panels which are inexpensive to manufacture such that the various tapered portions may simultaneously taper inwardly in more than one horizontal direction and that the widths of all water tube panels remain substantially uniform in the tapered portions.
In one aspect, my invention relates to a vertical polygonal heat exchange chamber including an upper opening, a lower opening, and an enclosure formed between the upper and lower openings. The enclosure includes at least one tapered portion that narrows in a direction toward one of the openings. The tapered portion is lined with N first water tube panels arranged adjacent to and alternately with N second water tube panels, where N is an integer greater than two. Each of the first and second water tube panels is angled inwardly from the widest part of the tapered portion toward the interior of the enclosure, with each of the first water tube panels being angled inwardly to a greater degree than each of the second water tube panels.
The heat exchange chamber according to this aspect of my invention may also include a vertically-extending portion contiguous with the tapered portion. The vertically-extending portion has a substantially uniform horizontal cross section and is lined with a plurality of vertical or substantially vertical water tube panels that comprises generally vertical extensions of the first and second water tube panels that line the tapered portion.
The inner surface of each second water tube panel (i.e., the surface facing the interior of the enclosure) is joined, preferably by welding, to respective side edges of the two first water tube panels adjacent to that panel. In that way, the first and second water tube panels form a gas-tight enclosure for the tapered portion.
Each of the first and second water tube panels preferably includes a plurality of individual water tubes. The spacing between each water tube preferably is substantially constant within each of the first and second water tube panels. However, the spacing between individual tubes in different panels can vary. For example, the spacing between the tubes in the first water tube panels can be different from the spacing between the tubes in the second water tube panels. Each of the first and second water tube panels preferably is substantially uniform in width. According to a preferred embodiment, all panels of the water tube panel lining in the tapered portion of the heat exchange chamber are of equal width. Alternatively, the water tube panels can have different widths, with the second water tube panels being wider than the first water tube panels, for example. In either case, the water tube panels are planar or substantially planar.
At the level where the tapered portion is narrowest, respective side edges of each pair of adjacent first water tube panels can be joined to form one of the openings of the chamber. The first water tube panels can extend vertically beyond the opening to form a vertically-extending end channel for discharging separated particles from the chamber, for example.
The individual water tubes of the first water tube panels can be connected at the end edges of the panels to a common header at the level where the tapered portion is narrowest. Similarly, the water tubes of the second water tube panels can be connected at the end edges of the panels to a different common header. If necessary, the water tube panels can be angled outwardly away from the interior of the enclosure before the water tubes are connected to their respective headers. According to a preferred embodiment, each header is arranged parallel to a substantially horizontal plane.
The heat exchange chamber can be provided with a tapered portion lined with water tube panels, as described above, near one or both of its ends. Each tapered portion tapers inwardly simultaneously in more than one horizontal direction in such a way that the width of each water tube panel remains substantially uniform.
In the heat exchange chamber according to the present invention, the lining of the tapered portion is formed by a simple and easy method using simple water tube panels which are inexpensive to manufacture. Because the width of each panel in the tapered portion of the heat exchange chamber is substantially uniform, problems caused by tubes of different lengths are avoided.
Advantageously, any headers are arranged parallel to a substantially horizontal plane. That way, problems associated with the use of inclined headers are avoided. For example, if a horizontal or approximately horizontal header contains a mixture of steam and liquid water, such mixture will be evenly distributed throughout the header, whereas in an inclined header, the steam and liquid water may tend to flow toward different portions of the header. Furthermore, the use of horizontal or approximately horizontal headers facilitates the even distribution of the heat exchange medium (e.g., liquid water, steam, or a mixture thereof) to the individual water tubes of the panels. Furthermore, the number of the headers can be minimized, because in each of the panels all tubes are of the same length and when so desired, the tubes of different panels may be joined to the same header.
The present invention provides a simple way to line a heat exchange chamber throughout with water tube panels. Thus, it provides a way to avoid thick refractory coated portions of such chambers and problems related, e.g., to the durability of such structures.
According to the invention, the heat exchange chamber may be a heat exchange chamber for recovering heat from flue gases or from a suspension of flue gases and solids. In a preferred embodiment, the heat exchange chamber is part of a fluidized bed reactor, especially the body of a cyclone of a fluidized bed reactor.
In another aspect, my invention relates to a vertical polygonal heat exchange chamber again including an upper opening, a lower opening, and an enclosure formed between the upper and lower openings. In this aspect, however, the enclosure includes (i) a first portion having a number of vertically-extending sides equal to two times N, where N is an integer greater than two, and (ii) a tapered second portion, contiguous with the first portion, that narrows in a direction leading away from the first portion. The second portion is lined with N first water tube panels arranged adjacent to and alternately with N second water tube panels. Each of the first and second water tube panels is angled inwardly from the widest part of the second portion toward the interior of the enclosure, with each of the first water tube panels being angled inwardly to a greater degree than each of the second water tube panels.
In still another aspect, my invention relates to a method of lining a tapered portion of a vertical polygonal heat exchange chamber with a number of water tube panels equal to two times N, where N is an integer greater than two. The method includes steps of (i) arranging N first water tube panels adjacent to and alternately with N second water tube panels, and (ii) angling each of the first and second water tube panels inwardly from the widest part of the tapered portion toward the interior of the heat exchange chamber, with each of the first water tube panels being angled inwardly to a greater degree than each of the second water tube panels.